Bicycle Wheel Nut Design: Material Selection and Heat Treatment Considerations

[louie13]

Hello everyone,

I am currently trying to design some custom nuts for my bmx wheel axle but I have a few questions which I thought you guys might be able to help me with.
First of all I've created an autodesk inventor model of the flange style nut I want to create but I'm not sure what material would be best to use for this application. I currently have stunt pegs on my bike too meaning a lot of extra forces will be transmitted through the axle and into the nut & dropout of the frame. Some commonly used materials for nuts are stainless steel (not the strongest but corrosion resistant which is useful), alloy steel, tianium or 7075 aluminium alloy. I currently have an aluminium and a stainless bolt on either side of the rear axle as one of my aluminium ones split which is why I want to machine custom ones.
I've been thinking of using a steel alloy such as 4130 and heat treating it. This would be very strong but could be too ridgid considering the forces being put through it, making it likely to snap rather than bend when load is applied. Another material I've thought about using is grade 5 titanium due to its high strength and more "springy" properties compared to 4130 which could be useful for the situation. Now I'm only a high school student, not a mechanical engineer so I could be thinking about this completely wrongly.

Another question I have is about washers to acompany these bolts. I'm just wondering if a nord-lock style or oversized flat washer would have any major advantages over a regular flat washer regarding strength and the prevention of the axle moving in the dropouts from peg use since I can't install chain tensioners.

I hope you all can understand what I mean, I'd be happy to try and explain anything any further and any suggestions about the engineering of the nuts is more than welcome.

 

[Nidum]

First of all I've created an autodesk inventor model of the flange style nut I want to create

Can we have a look ??

 

[louie13]

Can we have a look ??

I've attached a quick render I created with no specified material.

 

[billy_joule]

What problem are you trying to solve?
Why can't OTS (off the shelf) nuts be used?

 

[louie13]

What problem are you trying to solve?
Why can't OTS (off the shelf) nuts be used?

I thought it would be a fun project and I'd like to make them for use with a 19mm socket for extra strength rather than 17mm that other companies use.

 

[Ketch22]

One quick addition to your original post. Please do not confuse heat treatment with making it hard. A heat treatable Ferris alloy like 4130 would be a good choice among others. The process of heat treatment is just using heat to alter the structure of the metal. It is normal to search the balance between hardness and malleability appropriate for the job. This is how things like chisel can have a very hard edge with a highly ductile body and exceptional impact resistance all in the same piece of metal. We can just define the right process to achieve best results once the plan is set.

 

[louie13]

One quick addition to your original post. Please do not confuse heat treatment with making it hard. A heat treatable Ferris alloy like 4130 would be a good choice among others. The process of heat treatment is just using heat to alter the structure of the metal. It is normal to search the balance between hardness and malleability appropriate for the job. This is how things like chisel can have a very hard edge with a highly ductile body and exceptional impact resistance all in the same piece of metal. We can just define the right process to achieve best results once the plan is set.

Thanks a lot for clearing that up, I don't know much about the types of heat treatment, much appreciated. I think a treatment like you described would be best to achieve high strength and hardness in the thread but not too hard that it makes the whole bolt not very effective when it comes to impact resistance.